The Brain Is the Rate-Limiting Organ of Longevity: A Brain-First Systems Framework for Aging.

Longevity research has traditionally emphasized peripheral organ systems, metabolic optimization, and molecular aging pathways, while comparatively neglecting the central nervous system as the primary determinant of healthspan. This editorial advances the thesis that the brain functions as the rate-limiting organ of longevity. Drawing on systems neuroscience, clinical neurology, and evidence from neuropsychiatric and neurodegenerative disease, it is argued that progressive disruption of neural networks governs functional decline across multiple physiological systems, regardless of peripheral biological age. Cognitive resilience, autonomic regulation, sleep integrity, affective stability, and behavioral capacity are centrally mediated processes that determine an individual's ability to maintain homeostasis over time. When brain function deteriorates, lifespan may persist, but meaningful healthspan collapses. A Brain-First Longevity Framework (BFLF) is proposed that prioritizes preservation and restoration of neural network function as foundational to extending durable, functional longevity. BFLF has direct implications for clinical practice, therapeutic development, and the future architecture of longevity medicine.